The invention relates generally to electro mechanical and piezoelectric biomedical controllers, and more specifically, it relates to a stability augmentation system.
With old age, people tend to develop a jitter which is a direct result of degeneration of their nerves. Since both the nerves and the brain control area have degenerated to a point where there is a significant lag between knowledge of the position of the body part and commands from the brain that move the muscles and affect the position of the body part. Patented art of interest includes the following U.S. Patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 6,356,784, Mar. 12, 2002, Method of treating movement disorders by electrical stimulation and/or drug infusion of the pendunulopontine nucleus, Lozano, Andres M;
U.S. Pat. No. 6,695,794, Feb. 24, 2004, Active tremor control system, Kaiser, Kenneth W. et al;
U.S. Pat. No. 6,323,391, Nov. 27, 2001, Methods and transgenic mouse model for identifying and modulating factors leading to motor neuron degeneration, Schlaepfer, William W;
U.S. Pat. No. 5,643,329, Jul. 1, 1997, System for maintaining a desired spinal curvature of a user suffering from improper alignment of the vertebrae of the spine, Solomonow, Moshe;
U.S. Pat. No. 5,551,445, Sep. 3, 1996, Apparatus and method for movement coordination analysis, Nashner, Lewis M.;
U.S. Pat. No. 4,712,558, Dec. 15, 1987, Electrical stimulation of muscle, Kidd, Geoffrey;
U.S. Pat. No. 6,234,045, entitled Active Tremor Control issued to Ken Kaiser;
U.S. Pat. No. 6,839,594, entitled Actuation and Control of Limbs Through Motor Nerve Stimulation issued to Cohen et al.
The Lozano patent describes techniques for treating movement disorders by electrical stimulation and/or drug infusion. It utilizes an implantable signal generator and an electrode and/or an implantable pump and catheter. High electrical stimulation pulses and/or drug therapy is provided to the Pedunculopontine Nucleus (PPN). A sensor is also used to detect various symptoms of the movement disorders with a microprocessor algorithm to analyze the output from a sensor to regulate the stimulation and/or drug therapy delivered to the PPN.
The Schlaepfer patent describes methods of identifying factors involved in motor neuron degeneration by identifying factors affected by alterations in a C-binding complex of a ribonucleotide protein complex isolating and purifying the factors or nucleic acid sequences encoding the factors in a transgenic mouse.
The Solomonow patent describes a system for maintaining a desired spinal curvature of a user suffering from improper alignment of the vertebrae of the spine. In its broad aspects, it comprises a sensor feedback system and electrodes. The sensor feedback systems measures spinal curvature, determines whether selected conditions have been met warranting the application of electrical stimulation and provides information regarding the determination of an electronic stimulator. The electrodes are space ably mounted on selected portions of the user's back. They are in electrical communication with the electronic stimulator for casing contraction of the back muscles at selected levels, thus providing alignment of the spinal vertebrae. The sensor feedback system includes a sensor assembly which comprises an upper elongated rigid segment, a lower elongated rigid segment and a sensor.
U.S. Pat. No. 5,551,445 describes methods and devices are provided for evaluating among the limbs of a subject the distribution of impairments of the subject's ability to coordinate the muscular contractions to execute effective postural movements. The subject may be placed on two independently movable support surfaces, either of which may be fixed or sway-referenced. The subject's ability to maintain his or her equilibrium position is then monitored.
The Kidd patent describes a method and apparatus are disclosed for the electrotrophic stimulation of muscle, that is, stimulation using pulses trains onto which information which will cause long-term functional and/or structural changes in the muscle tissue. This information is coded into the interval between successive pulses of the series. Also disclosed is a method and apparatus for acquiring trophic data from motor until action potential series.
Patients with neurodegenerative diseases or trauma like cerebral infarct or spinal cord injury can have a variety of movement and muscle control problems, like resting, postural, intention or action tremor; dystonia (improper muscle tone); spasticity (undesirable movements, or muscle co-contraction); dyskinesia (poorly executed movements) or involuntary movements like ballismus, choreiform movements are torticollis (inappropriate movements or limbs control). Many of these problems can be called hyperkinesias. Although they can be chronic, or worse, progressive, they also may have times of relative remission. Such problems are found, at certain stages, for patients with Parkinson's disease, multiple sclerosis, cerebral palsey, secondary to deafferentation pain, post stroke, pose apoplexy or anoxia, post head or spinal trauma, post poisoning, cerebella disease etc. Dyskinesia also may result from long term usage of levodopa or other especially for Parkinson's patients.
A number of techniques are used for treating these and other movement disorders. Electrical stimulation and drug infusion techniques have become increasingly popular. In the case of electrical stimulation, an electrical lead having one or more electrodes is typically implanted near a specific site in the brain or spinal cord or a patient. The lead is coupled to a signal generator which delivers electrical energy through the electrodes to nearby neurons and neural tissue. The electrical energy delivered through the electrodes creates an electrical field causing excitation or inhibition of the nearby neurons. For example stimulation of the vagus nerve as described in U.S. Pat. Nos. 4,702,254; 4,867,164; and 5,025,807 has been used to reduce the likelihood that a person with epilepsy will experience a seizure. For example, U.S. Pat. No. 5,716,377 entitled “Method of Treating Movement Disorders by Brain Stimulation” discloses techniques for stimulation of various portions of the brain.
The systems cited above can be improved since the response delay can be directly modeled as a time lag in a control system. The system itself could theoretically be modeled, as least on first pass, as a linear second order system with a certain crossover and phase margin. The muscles provide a force and yield an acceleration. The eyes and other feedback mechanisms yield position (as well as velocity). As the response time increases, the modeled time delay increases. At a lower phase margin, the control system becomes oscillatory and marginally stable. There are higher orders damping terms that help keep the system stable where it would be modeled as unstable. The introduction of damping or additional feedback loops into this system could potentially stabilize or reduce jitter in the system. The likely result is a reduced bandwidth system that has a higher phase margin and lower crossover frequency.